Field
The disclosure relates generally to power supply circuits and methods and, more particularly, to inductive boost type converters, circuit and a method thereof.
Description of the Related Art
Low dropout (LDO) regulators are a type of voltage regulators used in conjunction with semiconductor devices, integrated circuit (IC), battery chargers, and other applications. Low dropout regulators (LDO) can be used in digital, analog, and power applications to deliver a regulated supply voltage.
In an example known to the inventor, a low dropout (LDO) regulator output stage is shown in FIG. 1. FIG. 1 illustrates a typical implementation of a boost DC/DC output stage supplying a load in the form of a Class D speaker amplifier. The circuit comprises a battery source input voltage VIN=VBATTERY 10, a ground reference 20, and output voltage VOUT=VBOOST 30. The output load consists of a Class D amplifier 40, and capacitor 60. The input voltage signal has a series inductor 50 which is electrically connected at node LX 55 to the p-channel MOSFET output pull-up transistor drain 70 and to the n-channel MOSFET output pull-down transistor drain 80. The high side (HS) p-channel MOSFET pull-up output stage is connected to the high side (HS) driver 75 (e.g. also noted as a “pre-driver”). The input of the high side (HS) driver (pre-driver) 75 is electrically connected to the input signal PWM (P) 77. The high side (HS) p-channel MOSFET pull-up output stage is connected to the high side (HS) driver 75. The input of the high side (HS) pre-driver 75 is electrically connected to the input signal PWM (P) 77. The low side (LS) n-channel MOSFET pull-down output stage 80 is connected to the low side (LS) driver 85 (e.g. pre-driver). The input of the low side (LS) pre-driver 85 is electrically connected to the input signal PWM (N) 87.
As illustrated in FIG. 2, a system with both low drop-out (LDO) and boost operation known to the inventor is shown. FIG. 2 shows a input voltage VIN 110, a ground rail 120, an output voltage VOUT 130, a load 140, an inductor 150, a capacitor 160, a low dropout (LDO) function 170, and boost function 180. In conventional implementations and when a linear mode is needed an extra power device is added between the battery (e.g. VIN) and the output voltage VOUT. A power device, referred to as high side (HS) is put in an “off-state” in order for the extra power device to drive the load and output voltage (VOUT) in a linear mode.
In this implementation, the usage of a low dropout (LDO) and boost mode device requires additional silicon area and semiconductor chip size. Additionally, the need for extra circuitry leads to unwanted conduction during switching modes. It would be desirable to eliminate the need for an extra power device to achieve the same functional objective. It would also be desirable to simplify the network to avoid additional circuitry and achieve a linear LDO mode.
In low dropout (LDO) regulators, a DC-DC converter having a low side pre-driver has been discussed. As discussed in published U.S. Pat. No. 8,049,479 to Shiraishi et al, a DC/DC converter package having separate logic and power ground terminal is described where a DC-DC converter having a low side pre-driver driving a low side MOSFET, and a portion for a main circuit passing through a high side is disclosed.
In low dropout regulators, a DC-to-DC converter having a low side pre-driver driving a low side MOSFET, and a portion for a main circuit passing through a high side has been discussed. As discussed in published U.S. Pat. No. 7,821,243 to Shiraishi et al, a DC-DC converter having a low side pre-driver driving a low side MOSFET, and a portion for a main circuit passing through a high side is shown. The implementation also uses a PWM, VGL pre-drive, and VGH pre-drive.
In low dropout (LDO) regulators, control methods exist for plurality of DC-DC converters. As discussed in published U.S. Pat. No. 6,809,678 to Vera et al, shows a plurality of DC-to-DC converters each contains a power section controller calibration to provide matching of control parameters. Data processing controlled DC-to-DC converter system and method of operation are highlighted.
Methods and apparatus for multiple converters has been shown. As discussed in published U.S. Pat. No. 6,414,856 to Ambatipudi et al. describes a high precision output voltage matching in a multiple output power converter.
Matching is further highlighted in power converters. As discussed in published U.S. Pat. No. 4,607,323 to Sokal et al shows a power converter with a matching network between the output of Class E dc/dc inverter and input of rectifiers. Class E high frequency high efficiency dc/dc power converter are discussed.
In these embodiments, the solutions to improve the response of the low dropout (LDO) regulator, and more specifically DC-to-DC converters utilize various means to address matching.